Bleaching of sponges



Patented Mar. 28, 1944 BLEACHING OF SPONGES Harlow G. Hyatt, Buffalo, N.Y., assignor to Buffalo Electro-Chemical Company, Inc., Buffalo,

No Drawing. Application November 30, 1940, Serial No. 368,039

2 Claims.

The present invention relates to the cleaning and bleaching of spongesand more particularly to a treatment wherein sponges of exceptionallylight color may be produced.

Sponges, as they appear on the market in the crude state, are very darkin color and are filled with a considerable amount of inorganic foreignmaterial.

It has been proposed heretofore to prepare sponges of a leveled color bytreatments which eliminate a considerable portion of colored materialfrom the sponge and, in addition, remove some of the inorganic coloringmaterial. These treatments, however, are not for the production of asponge of light color but for the production of a sponge of even levelcolor. In general, such treatments were carried out by first treatingthe sponge with acid and thereafter with permanganate. The resultingsponge was brown in color and relatively free of inorganic material.

It is an object of the present invention to provide a method forpreparing sponges of very light color as demanded by certain types ofmarket.

In accordance with the procedure of the present invention, the sponge inthe unbleached conditionis soaked in water for a considerable period oftime under conditions wherein inorganic matter is rendered soluble andis removed from the sponge. Due to the large apparent volume of thesponge in the Wet condition, extremely large liquor ratios are employedand in general a ratio of treating solution to sponge of about 20 to 1is found to be suitable. In order to remove the inorganic material fromthe sponge, the treating solution should contain in 1,000 ccs.suificient acid, such as hydrochloric or other mineral acid to formsoluble salts with the inorganic material. In general, ccs. ofconcentrated hydrochloric acid to 1,000 cos. of solution will be foundsuitable. This acid attacks lime and calcium salts as well as otherminerals occurring in the sponge to produce soluble chlorides thereof.In order to eliminate certain combinations of iron. a fluoride, such assodium fluoride or sodium bifiuoride, is added in desirable quantities,and in general about 5 grams of sodium bifiuoride will be foundsufii'cient. After the sponges have steeped in the bath for about threehours at room temperature. or moderately elevated temperature, or in anyevent for a time sufficient to dissolve the inorganic impurities. thesolution is drained off and the sponges rinsed and squeezed out inwater.

After the cleaning action of the acidified solution upon the sponge iscomplete, the sponge is then given a preliminary treatment which, initself, is not a bleaching treatment for the reason that, although thecolor of the sponge is lightened, color returns in the sponge uponstanding. This preliminary treatment comprises a treatment of the spongeat room or slightly elevated temperatures by immersion in a high liquorratio bath of about 20 to 1 containing in 1,000 ccs. about 3 grams of asoluble chlorite and acidified with an acid, as, for instance, sulfuricacid or other suitable acid. The amount of acid will be sufficient toreduce the pH of the bath to a point at which the chlorite forms C102 atthe temperature employed, and for the amount of chlorite suggestedabove, 2 cos. concentrated sulfuric acid will be found suflicient. Itwill be understood that where sponges contain very considerable amountsof the dark red colors, the amount of chlorite may be increased to about5 grams per liter. After steeping for about three hours, the sponges areremoved, rinsed and squeezed out with water. Although some lightening incolor is obtained, it is not possible to obtain fully bleached spongesby the employment of the soluble chlorite alone. Furthermore, colorsobtained by the chlorite treatment are not stable since the spongegradually reacquires color on standing.

In accordance with the procedure of the present invention, bleachedstable end colors in the sponge are obtained by treating the sponge,subsequent to the preliminary treatment with the soluble chlorite, witha peroxide or percom- 2 pound, such as peroxides of hydrogen, sodium,potassium, or other alkali metals, or the peroxides of alkaline earthmetals, as well as persalts, such as soluble perborates, percarbonates,

persilicates, and the like, all designated herein as peroxides. Thesponge, after being treated with the chlorite and rinsed, is steeped ata liquor ratio of about 20 to 1 in a peroxide bleach bath at a moderatetemperature, i. e., either room temperature or temperatures up to aboutC. This steeping is carried out until the proper bleached condition isobtained and in eneral requires about 2 to 20 hours, more or less. Thebleach bath should, in addition to the peroxide, contain some materialrendering the bath slightly alkaline but not so alkaline as to damagethe sponge. In general, mild alkalies are suitable for this purpose,such as ammonia, bicarbonate, pyrophosphate, and the like. Additionally,certain salts aiding the bleaching action may be present. A formulationthat has been found eminently suitable and has been given for purposesof illustration only is as follows:

In 1,000 cc. solution 100-volume hydrogen peroxide cc 20 Sodiumpyrophosphate g 5 Sodium oxalate g 5 It will of course be understoodthat this composition may be varied within rather wide limits, keepingin mind that the alkalinity should not be too great and that thetemperature should not be so high as to produce damage in the spongestructure or fiber. After steeping for the requisite time in theperoxide bleach bath, the sponge is rinsed and squeezed out. It is anexcellent, even, level color with a very slight yellow cast of the typedemanded in certain trades and, furthermore, is of a color permittingthe sponge to be dyed with fast colors and particularly the desirablepastel shades.

From the foregoing it will be seen that the present invention provides amethod for the production of sponges of very light, level colors and inexcellent bleached condition without damage to the sponge while at thesame time foreign, inorganic matter is removed from the sponge,

What is claimed is:

1. The method of treating sponges to lighten the color thereof whichcomprises washing the sponge with dilute acid to remove inorganic matterand then immersing the sponge in an acidified solution of a solublechlorite and thereafter steeping the sponge in a slightly alkalineperoxide solution.

2. The method of treating sponges to lighten the color thereof whichcomprises washing the sponge with dilute acid to remove inorganic matterand then immersing the sponge in an acidified solution of a solublechlorite and thereafter steeping the sponge in a slightly alkalineperoxide solution at a moderate temperature and until the sponge isbleached.

HARLOW G. I-IYATT.

